@totemsdk/pubsub-transport

Publish-subscribe transport abstractions for the Totem SDK — MQTT-compatible interfaces and in-process implementations for wiring and testing pub/sub message flows.

Exports

| Export | Description | |---|---| | IPubSubTransport | Canonical pub/sub interface (MQTT semantics) | | PubSubMessage | Inbound message type { topic, payload } | | PubSubSubscription | Subscription handle with unsubscribe() | | EventEmitterTransport | In-process EventEmitter-backed transport | | MockPubSubTransport | Test mock with inject() and recorded calls | | MqttClientPort | Type alias for IPubSubTransport (backward compat) | | MqttMessage | Type alias for PubSubMessage |

Installation

npm install @totemsdk/pubsub-transport

No required peer dependencies — purely Node.js built-ins.

Quick start

import {
  EventEmitterTransport,
  createPairedEventEmitterTransports,
  MockPubSubTransport,
} from '@totemsdk/pubsub-transport';

// Bidirectional in-process pair
const [alice, bob] = createPairedEventEmitterTransports();
await alice.connect();
await bob.connect();

bob.onMessage((msg) => console.log('bob got', msg.topic, msg.payload));
await alice.subscribe('updates');
await alice.publish('updates', new TextEncoder().encode('hello'));

// Mock transport for unit tests
const mock = new MockPubSubTransport();
await mock.connect();
await mock.publish('foo', 'bar');
console.log(mock.published); // [{ topic: 'foo', payload: 'bar' }]
mock.inject('incoming', 'data'); // simulate broker delivery

Implementing a custom transport

import type { IPubSubTransport, PubSubMessage, PubSubSubscription } from '@totemsdk/pubsub-transport';

class MyTransport implements IPubSubTransport {
  async connect() { /* ... */ }
  async disconnect() { /* ... */ }
  async subscribe(topic: string): Promise<PubSubSubscription> { /* ... */ }
  async publish(topic: string, payload: string | Uint8Array): Promise<void> { /* ... */ }
  onMessage(handler: (message: PubSubMessage) => void): () => void { /* ... */ }
}

License

MIT